1. Field of the Invention
The invention relates to a shaftless spinning rotor of an open-end spinning machine, which is electrically drivable with a single motor and which includes a spinning cup that receives fibers to be spun and an electric rotor disposed on the spinning cup, wherein the spinning rotor forms an axial field motor through a magnet and gas bearing with a stator.
As the development of rotor spinning machines progresses, the goal is not only to improve the quality of the yarns produced, but above all to increase production. A key role in increasing production is played by the rotary speed of the spinning rotor. For that reason, the most various kinds of drives and bearings for spinning rotors have been developed, in order to reach rotary speeds of markedly over 100,000 rpm. Reducing the rotor diameter and mass and lowering friction losses permits not only a higher rotary speed, but also reduced energy consumption when driven.
In that respect, shaftless spinning rotors, which are constructed as the rotor of an axial field motor, can be considered especially advantageous. A combined magnet and gas bearing assures relatively low friction losses.
A shaftless open-end spinning rotor for a combined magnet and gas bearing is known from Published International Application WO 92/01097. The shaftless spinning rotor described therein includes a spinning cup which receives the fibers to be spun, and an electric rotor disposed on the spinning cup and cooperating with a stationary stator.
Given the high yarn quality demanded today, the service life of the spinning rotor is limited by wear in the spinning groove, so that after a certain time, replacement of the spinning rotor is inevitable.